Sub woofer



FIG. 1 is an isometric view of a sub woofer showing my new design;

FIG. 2 is a rear view;

FIG. 3 is a front view;

FIG. 4 is a right side view;

FIG. 5 is a left side view;

FIG. 6 is a top view; and,

FIG. 7 is a bottom view.

FIGS. 4 and 5 are on a reduced scale. 

The ornamental design for a sub woofer, as shown and described. 